The present invention relates to door closers, and more particularly, to pneumatic door closers.
Pneumatic door closers are widely used because they allow a door to be opened readily and closed more slowly to avoid striking the person passing through the door frame and to avoid impacts upon closing to minimize damage to the hinges and latch.
Some prior art door closers employ numerous parts which increase the cost of fabrication and tend to decrease life and reliability. To obtain good sealing action of the piston as it moves to the closing position requires close control over the tolerances of the piston and cylinder and of the sealing ring which is generally used. Metal pistons require accurate and frequently separate manufacturing operations such as stamping and welding, increasing cost.
Assembly of the piston from stamped metal parts generally has required welding which produces distortion, requires venting of welding fumes, and produces sparks and pinch points.
It is an object of the present invention to provide a novel pneumatic door closer which utilizes a synthetic resin piston which provides inherent lubricity.
It is also an object to provide such a door closer in which the piston is formed with accurate contours leading to optimal performance.
It is a further object to provide such a door closer in which the components may be fabricated readily and economically and readily assembled without welding to provide reliability and long lived operation.